What do the following two equations represent? $-4x-4y = -5$ $4x-4y = 1$
Solution: Putting the first equation in $y = mx + b$ form gives: $-4x-4y = -5$ $-4y = 4x-5$ $y = -1x + \dfrac{5}{4}$ Putting the second equation in $y = mx + b$ form gives: $4x-4y = 1$ $-4y = -4x+1$ $y = 1x - \dfrac{1}{4}$ The slopes are negative inverses of each other, so the lines are perpendicular.